The present invention relates to generally a globoid worm gear generating method and more particularly an improvement of a method for generating globoid worm gears having developable tooth surfaces.
The inventors reported "the basic member gear theory" in KIKAI GAKKAI RONBUN (Journal of Japan Society of Mechanical Engineers), 1955, Vol. 21, No. 102, Page 164, Sakai as well as "the secondary action theory" in the same, 1972, Vol. 38, No. 311, Page 1895, Sakai and Maki. High efficiency of globoid worm gears generated based on the above two theories has been proved and widely accepted in the art.
In generating the globoid worm gears having developable tooth surfaces (of the type reported in KIKAI GAKKAI DOENSHU RONBUN (Reports in Conference held by Japan Society of Mechanical Engineers), No. 740-15), (1) the intermediate gear tooth surface is a plane, and (2) the plane is in parallel with the axis of an intermediate gear. These conditions have restricted the freedom of globoid worm gear design, especially the design of low-gear-ratio worm gears.
In addition, there has been a defect that because of the use of a tool representing a plane, both the tooth surfaces of a worm cannot be generated simultaneously.